Lecture Notes – Dermatology Eleventh Edition 11e eBook [PDF] Download
Lecture Notes – Dermatology Eleventh Edition 11e
It is essential to have some background knowledge of the normal structure and function of any organ before you can hope to understand the abnormal. Skin is the icing on the anatomical cake, it is the decorative wrapping paper, and without it not only would we all look rather unappealing, but also a variety of unpleasant physiological phenomena would bring about our demise.
You have probably never contemplated your skin a great deal, except in the throes of narcissistic admiration, or when it has been blemished by some disorder, but hopefully by the end of this first chapter you will have been persuaded that it is quite a remarkable organ, and that you are lucky to be on such intimate terms with it.
The epidermis is a stratified squamous epithelium, with several well – defi ned layers. The principal cell type is known as a keratinocyte .
Keratinocytes, produced by cell division in the deepest layer of the epidermis (basal layer), are carried towards the skin surface, undergoing in transit a complex series of morphological and biochemical changes known as terminal differentiation (keratinization) to produce the surface layer of tightly packed dead cells (stratum corneum or horny layer) which are eventually shed. In health the rate of production of cells matches the rate of loss so that epidermal thickness is constant. Epidermal kinetics are controlled by a number of growth stimulators and inhibitors.